The Effects of Topical Cannabidiol Cream on Post-exercise Recovery

Intro Canabidiol (CBD), a non-intoxicating cannabinoid, has recently stimulated great interest in the scientific community with an increased number of publication in the last decade. While it was first isolated and reported in 1963, subsequent studies were not published until the late 2000s. These studies have mainly focused on the effects of CBD on pain management, and anti-inflammatory processes Current evidence indicates that CBD plays a role in anti-inflammatory and antioxidant processes. CBD has been shown to act as an agonist for ionotropic cannabinoid receptors including chemo- and thermosensitive members of the Transient Receptor Potential (TRP) channel superfamily. This is important as this mechanism may decrease neuropeptide expression, and in turn decreases the release of pro-inflammatory cytokines and chemokines such as interleukin 1 alpha (IL-Iα), interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), and cyclooxygenase-2 (COX-2).

The application of CBD use varies, as it can be consumed orally as an oil, inhaled as a high concentration vape oil, or be applied topically. Although oral bioavailability of CBD is limited, recent research has shown that a single, oral dose (1500-6000mg) can still reach peak plasma concentrations of ~0.9 - 2.5 micrometers (uM) within ~4-5 hours with a half-life of ~14-17 hours (Taylor et al., 2018). Further, evidence suggests that ingested CBD can have a significant influence on the delayed onset of muscle soreness due to exercise-induced muscle damage, though the exact mechanisms were not. Conversely, recent evidence suggests that 150 mg of CBD oil had no effect on non-invasive markers of muscle damage in untrained men after 24 and 48 hours post-exercise. While inhaled CBD has not been studied thoroughly, a recent study in which participants vaporized 100 mg of CBD observed high blood CBD concentrations (104.6 ng/mL) after 30 minutes, although terminal half-life and max concentrations were not collected (Spindle et al., 2020). Still, an insufficiency in data regarding inhaled CBD is apparent. Given the low bioavailability of oral ingestion of CBD and the lack of research in inhaled CBD, the transdermal application may be an effective option. CBD has successfully been delivered transdermally in different animal species for anti-inflammatory activity and has indicated that topical application of CBD gel is an effective treatment for reduction in inflammation and hypersensitivity in rats. Specifically, research showed that a 6.2 mg/day dose optimally reduced swelling, while higher values (62.3 mg/day) did not yield additional improvements. These studies demonstrate transdermal administration of CBD may have therapeutic effects, although more research is necessary, especially as it pertains to humans.

In the context of sports, CBD's recent removal from the Prohibited List of the World Anti-Doping Agency (WADA) has no doubt aided in the increased use of CBD, especially considering that CBD is safe and well-tolerated at high doses (1,500 mg/day) or as an acute dose of 6,000mg. However, there are currently little evidence indicating that CBD may exert an ergogenic effect or accelerate/facilitate muscle recovery. In regard to potential ergogenic effects, no studies exist. While CBD may play a role in glucose metabolism and lipid storage via activation of Peroxisome proliferator-activated receptor ( PPARy), as well as increased activity of mitochondrial complexes, no data exists stating that it would aid in performance as an ergogenic. Thus, the majority of CBD use and studies have focused on recovery.

While CBD has been reported to exert a number of physiological, biomechanical, and psychological effects, the specific effects on human skeletal muscle, exercise recovery, and subsequent exercise performance are limited. Cannabinoid receptors (CB1) activation has been shown to increase AMP-activated kinase a1 (AMPKa1) messenger ribonucleic acid (mRNA) expression, which suggests that CB1 receptors are active in skeletal muscle. Still, these data are inconsistent, as blocking of CB1 pathways plays a permissive role for Anandamide (AEA) stimulation of AMP-activated kinase a2 (AMPKa2) in lean subjects, but it plays an inhibitory role in obese subjects.

In regard to exercise recovery, there is evidence in animal and cell studies that CBD may limit the harmful effects of inflammation by decreasing immune cell accumulation, stimulating production of anti-inflammatory cytokines, inhibiting production of pro-inflammatory cytokines, and attenuating reactive oxygen species. There is also evidence that CBD acts directly on muscle plasticity affecting quality and performance by modulating levels of myogenin and troponin-t-1 transcription levels. Further, evidence suggests CBD causes a significant reduction in all myogenic transcripts but does not reduce the expression of muscle differentiation markers, which may suggest it can attenuate inflammation without blunting muscular adaptations. In regard to the use of CBD on post-exercise markers in humans, there is evidence suggesting that the use of CBD can decrease delayed-onset muscle soreness (DOMS), although an apparent paucity exists. Comparatively, other evidence suggests that the use of CBD has no effect on DOMS, especially in untrained males. Exercise, especially when strenuous, and with a heavy eccentric component, can cause acute damage to skeletal muscle myofibrils and the surrounding extracellular matrix. Exercise-induced muscle damage (EIMD) can impair muscle function and initiate an inflammatory response. Although inflammation is necessary for EIMD repair and adaptation, excessive inflammation attenuates functional recovery and may contribute to prolonged muscle soreness. Based on the evidence from cell and animal studies, CBD could reduce inflammation and facilitate muscle recovery.